Holder for an electric lamp

ABSTRACT

A holder for an electric lamp which comprises a first contact element guided for movement through a plug of insulating material separating the lamp opening of the holder from the terminals, and furthermore comprises a second contact element located laterally of and in spaced relationship to the first contact element while being connected thereto to be brought into contact with its corresponding terminal as a result of the movement of the first contact element caused by introduction of the lamp. The first contact element on the side of the plug of insulating material which is facing away from the lamp opening and by means of an insulating carrier carries the second contact element so as to make the latter tiltable and restrictedly displaceable along the axis of the lamp holder. The terminal corresponding to the second contact element and a lateral contact spring leading to the side of the plug of insulating material facing the lamp opening are each provided at points spaced from each other, with a conductive support point for the second contact element which latter is forced against the support points when making contact. When full contact pressure has been achieved, the terminal leading to the first contact element is situated at a lower level relative to the support points of the second contact element than is the case when there is no contact pressure.

United States Patent 1191 Glantz Oct. 28, 1975 HOLDER FOR AN ELECTRIC LAMP [75] Inventor: Lennart Glantz, Ostersund, Sweden [73] Assignees: Bertil Hellzn, As; Ulf Bjork,

Angelholm, both of Sweden 22 Filed: May 31, 1974 21 Appl.No.:474,924

Related US. Application Data [63] Continuation of Ser. No. 316,258, Dec. 18, 1972,

abandoned.

[30] Foreign Application Priority Data Feb. 23, 1972 Sweden 2203/72 [52] US. Cl. 339/64 R; 339/111; 339/176 L [51] Int. Cl. HOIR 13/62 [58] Field of Search 339/45, 64, 92, 176 L, 339/180,l11, 181,188,189

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 312,267 4/1929 United Kingdom 339/180 473,228 3/1929 Germany 339/180 248,108 1/1948 Switzerland 339/180 903,585 8/1962 United Kingdom... 339/59 L 472,593 3/1929 Germany 339/180 187,886 10/1966 U.S.S.R 339/111 Primary Examiner-Joseph H. McGlynn Attorney, Agent, or Firm-Walter Becker [5 7 ABSTRACT A holder for an electric lamp which comprises a first contact element guided for movement through a plug of insulating material separating the lamp opening of the holder from the terminals, and furthermore comprises a second contact element located laterally of and in spaced relationship to the first contact element while being connected thereto to be brought into contact with its corresponding terminal as a result of the movement of the first contact element caused by introduction of the lamp. The first contact element on the side of the plug of insulating material which is facing away from the lamp opening and by means of an insulating carrier carries the second contact element so as to make the latter til'table and restrictedly displaceable along the axis of the lamp holder. The terminal corresponding to the second contact element and a lateral contact spring leading to the side of the plug of insulating material facing the lamp opening are each provided at points spaced from each other, with a conductive support point for the second contact element which latter is forced against the support points when making contact. When full contact pressure has been achieved, the terminal leading to the first contact element is situated at a lower level relative to the support points of the second contact element than is the case when there is no contact pressure.

8 Claims, 7 Drawing Figures 1 HOLDER FOR AN ELECTRIC LAMP This is a continuation of application Ser. No. 3l6,258, filed Dec. 18, 1972, now abandoned.

This invention relates to a holder for an electric lamp the cap of which has a substantially centrally situated bottom contact and a side contact, which holder comprises a socket sleeve with a mounting for reception of the cap of the lamp, terminals for connection of electric conductors, and contact elements which are to establish contact between the cap contacts and the terminals, said contact elements being spring-loaded so as to be out of contact with the corresponding terminal when there is no lamp in the holder but being forced by the introduction of a lamp into the holder to make contact with the terminal against the spring force, a first one of the contact elements being guided for movement through a plug of insulating material which separates the lamp opening of the holder from the terminals, said contact element having further an end contact surface situated on the central axis of the socket sleeve and directed towards the lamp opening to establish contact with the bottom contact of the lamp, and an opposite end contact surface intended to establish contact with the corresponding terminal, a second contact element being situated laterally of and spaced from the first contact element and being connected thereto to be brought into contact with its corresponding terminal as a result of the movement of the first contact element caused by introduction of the lamp.

Such a holder is known through the Norwegian Pat. No. 67,544. In this known holder, the second contact element consists of a leaf spring which serves at the same time as a biasing member to keep the first contact element out of contact with its corresponding terminal when there is no lamp in the holder. The leaf spring is situated on the side of the plug of insulating material which is facing the opening of the lamp, and acts between a stop on the first contact element and the plug of insulating material, and is designed to make contact with the part of a corresponding terminal situated on the same side of the plug of insulating material. This known holder has several serious drawbacks. In the first place, manufacture of the lampholder is complicated by the use of one and the same spring both to establish electrical contact and to provide the necessary spring force. Although the leaf spring partly shields said part of the corresponding terminal from the lamp opening, it cannot prevent contact with the terminal from the outside, under unfavourable circumstances, by a pointed conducting object. Furthermore, all contact surfaces and particularly the one between the leaf spring and its ter minal, are accessible to contamination by dust and dirt which may after awhile adversely affect the contact making.

The aim of this invention has been to design a lampholder which has not the drawbacks of the kind referred to above.

This has been accomplished in that the first contact element on the side of the plug of insulating material which is facing away from the lamp opening and by means of an insulating carrier, carries the second contact element so as to make the latter tiltable and restrictedly displaceable along the axis of the lampholder; that the terminal corresponding to the second contact element and a lateral contact spring leading to the side of the plug of insulating material facing the lamp opening, are each provided, at a distance from each other,

with a conductive support point for the second contact element, the second contact element being forced against these support points when making contact; and that, when full contact pressure has been achieved, the terminal corresponding to the first contact element is situated at a lower level relative to the support points of the second contact element than when there is no contact pressure.

In the lampholder in accordance with the invention, all current carrying parts are effectively shielded from manual contact and the contact surfaces are inaccessible to contamination by dust and dirt. Furtheremore, a very large contact pressure is achieved at the contact surfaces, particularly due to the arrangement whereby the second tiltable contact element is pressed against the conductive support points to as to make contact with these.

The mechanical stability and high contact pressure capacity of the contact device can be further improved in a preferred embodiment of the invention in which a three-point support for the second contact element comprises, in addition to the said conductive support points, a third support point. This third support point may thereby also be conducting and connected to a second lateral contact spring leading to the lamp openmg.

The invention will now be described in greater detail below by reference to the attached drawing, in which FIG. 1 shows an end view as seen in the lamp introduction direction of an embodiment of the lampholder in accordance with the invention,

FIG. 2 shows a section in the direction of arrows ll-II in FIG. 1,

FIG. 3 shows the same section as FIG. 2 with a lamp screwed right down into the lampholder,

FIG. 4 shows a side view of a split contact housing for a movable contact device, which housing forms part of the lampholder,

FIGS. 5 and 6 show end views of the mating faces of the two parts of this contact housing both parts being shown with the movable contact device, and

FIG. 7 shows a side view, partly in section, of the contact elements carried by the lamp housing.

THe embodiment of the lampholder shown in the drawing is designed for a conventional electric lamp 2 the cap of which contains a substantially centrally situated base contact 4 and a side contact 6 extending around the cap, said side contact being insulated from the base contact. The lampholder comprises a split socket sleeve 8, 10 part 8 of which contains a threaded mounting 12 for the cap of the lamp.

Terminals l4, 16 provided for connection of electric conductors are carried in a round insulating contact plate 18 which, together with a wall or round plug 20 of insulating material and a side wall 22 in the form of a collar-shaped projection on the wall or plug 20 forms an enclosed housing with an inner space which accommodates the contact elements described in greater detail below. The housing 18-22 fits the socket sleeve in the way shown in FIGS. 2 and 3, whereby the bottom portion 10 of the socket has an opening 24 in its base to admit the electric conductors.

The lampholder comprises a contact assembly having a contact pin 26 for establishing contact between the base contact 4 and the terminal 14 said pin extending with same clearance through a central hole right through the plug 20 the length of the contact pin 26 being about twice the thickness of the plug 20 of insulating material. The contact pin 26 is surrounded by a compression coil spring 28 which, together with the contact pin, is guided with some clearance inside the hole through the plug 20 of insulating material and acts between a stop at the outer end of the contact pin and another stop, in the form of an annular projection 30, in the hole near the side of the plug 20 of insulating material which faces the inside of the lampholder. Owing to the fact that the contact pin also has some clearance in the projection 30, the contact pin is laterally tiltable to some extent, and this has some significance for the function of the pin as described in greater detail below. At its inner end, the contact pin 26 is surrounded concentrically and with some clearance by a round plate 32. The plate 32 is forced against an end flange 34 on the contact pin by a spring washer 36 which is fitted between the plate 32 and a locking washer 38 on the contact pin. Owing to the fact that the contact pin 26 has some clearance inside the plate 32, the plate is tiltable about the contact pin against the action of the spring washer 36. Around its periphery the plate 32 has a contact ring 40 one edge of which extends to some extent beyond the bottom face of the plate.

On the contact plate l8,there are three peripheralsupport points for the contact ring 40, one of which consists of the upper end of the terminal 16 and another one is formed by a part 41 of a contact spring 42 which is in contact with the plate 18. When the housing 18-22 is mounted, the contact spring 42 extends along the part 20 as shown in FIG. 4 and, at its outer end, is designed to make contact with the cap contact 6 on the lamp. The third support point 44 in the embodiment shown, only has the function of a support point in order to establish a three-point support for the contact ring 40 but also the third support point may be made to form part of a contact spring similar to the contact spring 42. When the projecting edge of the contact ring 40 is forced onto the three-point support described, the contact spring 42 is accordingly simultaneously brought into electrical contact with the terminal 16.

Whie the terminal 16 and also the other two support points of the three-point support are fixed, the terminal 14 which is to establish contact with the contact pin 26 is carried in the contact plate 18 in such a way that it is axially movable against the action of a spring washer 46 similar to washer 36.

On its outer side, the plug 20 of insulating material has a recess 48 concentric with the hole for the contact pin 26 to accommodate the end of the cap of the lamp. Although it is easy to dimension the spring 28 in such a way that a particularly heavy pressure is required on the end of the contact pin to have it to make contact, the recess 48 constitutes an additional safety measure against unintentional contact making, since the recess is sufficiently narrow to prevent the top of a normal finger from being pushed into it.

As will be seen particularly from FIG. 4, the contact housing 18, 20, 22, together with the contact elements enclosed in it in a dust-tight manner, the terminals l4, l6 and the contact spring 42 constitutes a contact device which is mountable in and demountable from the holder 8, as one unit. The contact spring 42, and the further contact spring, if any, are preferably attached to the part 20, 22 by means of a screw 50 as shown in FIG. 4.

THe function will be evident from the above description. When a lamp is screwed into the mounting 12, the base contact 4 first forces the contact pin 26 downwards against the action of the spring 28 until the contact ring 40 has been pressed against the threepoint support described, whereupon the lamp and the contact pin are further movable a small distance against the action of the spring washers 36 and 46 so that, when full contact pressure has been achieved, the contact surface of the terminal 14 is situated at a level which is lower relative to the support points of the three-point support than when there is no contact pressure.

The invention has a number of important advantages. The lampholder is practically completely safe from unintentional contact, since it is very difficult or almost entirely impossible to make contact by pressing down the contact pin by merely a finger, and all other contact parts are completely shielded. The contact surfaces which are to make contact with each other are furthermore, as described above, enclosed in a dust-tight manner so that dust and dirt cannot penetrate inside and, after a while impair the ability to make contact. By virtue of the stable three-point support arrangement for making contact with the cap contact 6, the device described, when the lamp is fully screwed home, provides a contact which is at all times very safe and has a low resistance.

Particular emphasis must also be laid on the fact that the contact pin 26 is guided only by the annular projection 30 which is centrally situated, both axially and radially, and has a slight extent in the axial direction. Thereby the least possible friction between the stud and the projection is obtained and the risk of the contact pin becoming jammed in the contact position is eliminated. The rotary movement of the contact pin when the lamp is screwed into the holder, which is relatively useless from the point of view of making contact, is damped and counteracted by the spring 28 which cannot, however, prevent movement along the periphery of the contact ring 40, of the spots of contact between the ring and the three-point support, which movement promotes a comparatively even wear.

The practically dust-tight enclosure of the contact surfaces in the contact housing 18, 20, 22 also has the effect that the lampholder is practically explosion proof, which can be improved further by introducing a sealing ring between 18 and 22.

I claim:

1. A holder for an electric light bulb, said bulb having a base with a center contact and a side contact, said holder comprising a socket at one end into which said bulb is pressed, two terminals for connection of electric conductors at the opposite end of said holder, said terminals being carried by a transverse plate at said opposite end, and a transverse, fixed wall intermediate said ends, one of said terminals being located in the center of said holder and the other at one side, a first, central contact element in the form of a contact pin mounted for movement through said fixed wall into contact with said center terminal by said bulb when pressed into said socket with said center contact in engagement with said first, central contact element, a spring resiliently holding said central contact element out of engagement with said center terminal unless engaged by a bulb, a fixed, lateral spring contact with one end on one side of said wall for engaging said side contact and extending toward said opposite end of said holder, with its other end on the other side of said wall, a second contact element carried by a transverse insulating carrier member mounted on said first contact element so as to be tiltable and restrictedly displaceable with respect thereto along the axis of the lamp holder, said second contact element being movable into engagement with the other end of said lateral spring contact and said side terminal by movement of said first contact element into engagement with said center terminal, said transverse plate together with said wall and side walls extending therebetween fonning an enclosed dustproof housing for said carrier member and said second contact element, said enclosed housing being removable from the holder as a unit together with the lateral contact spring and said first contact element.

2. A holder in accordance with claim 1, characterized in that a three-point support is arranged for the second contact element in its contact position, said three-point support comprising said other end of said lateral spring contact, said side terminal and a third support point.

3. A holder in accordance with claim 2, characterized in that said third support point is a conductive support point which is connected to a second lateral contact spring leading to the side of said wall which faces the lamp opening.

4. A holder in accordance with claim 2, characterized in that said insulating carrier member for the second contact element is in the form of a round plate concentrically arranged around the first contact element, and carrying at its periphery the second contact element in the form of a contact ring which projects to some extent beyond the side of the plate facing the terminals and that the support points of the three-point support are situated substantially in the same plane below the contact ring.

5. A holder in accordance with claim 4, characterized in that the first contact element extends with some clearance through a central hole in said round plate and is terminated by a flange carrying said round plate and that a spring washer is attached at its inner periphery to the first contact element and forces the plate against the flange.

6. A holder for an electric light bulb, said bulb having a base with a center contact and a side contact, said holder comprising a socket at one end into which said bulb is pressed, two terminals for connection of electric conductors at the opposite end of said holder, said terminals being carried by a transverse plate at said opposite end, and a transverse, fixed wall intermediate said ends, one of said terminals being located in the center of said holder and the other at one side, a first, central contact element in the form of a contact pin mounted for movement through said fixed wall into contact with said center terminal by said bulb when pressed into said socket with said center contact in engagement with said first, central contact element, a spring resiliently holding said central contact element out of engagement 6 with said center terminal unless engaged by a bulb, a fixed, lateral spring contact with one end on one side of said wall for engaging said side contact and extending toward said opposite end of said holder, with its other end on the other side of said wall, a second contact element carried by a transverse insulating carrier member mounted on said first contact element so as to be tiltable and restrictedly displaceable with respect thereto along the axis of the lamp holder, said second contact element being movable into engagement with the other end of said lateral spring contact and said side terminal by movement of said first contact element into engagement with said center terminal, said transverse plate together with said wall and side walls extending therebetween forming an enclosed housing for said carrier member and said second contact element, said enclosed housing being removable from the holder as a unit together with the lateral contact spring and said first contact element, said side walls being fixed to said wall and depending skirt-like therefrom.

7. A holder for an electric light bulb, said bulb having a base with a center contact and a side contact, said holder comprising a socket at one end into which said bulb is pressed, two terminals for connection of electric conductors at the opposite end of said holder, said two terminals carried by a transverse plate at said opposite end, and a transverse fixed wall intermediate said ends, one of said terminals being located in the center of said holder and the other at one side, a first, central contact element mounted for movement through said fixed wall into contact with said center terminal by said bulb when pressed into said socket with said center contact in engagement with said first, central contact element, a spring resiliently holding said. central contact element out of engagement with said center terminal unless engaged by a bulb, a fixed, lateral spring contact with one end on one side of said wall for engaging said side.

contact and extending toward said opposite end of said holder, with its other end on the other side of said wall, a second contact element mounted on and movable by said first contact element and insulated therefrom, said second contact element being movable into engagement with the other end of said lateral spring contact and said side terminal by movement of said first contact element into engagement with said center terminal, said transverse plate together with said wall and side walls extending therebetween forming an enclosed dustproof housing for said carrier member and said second contact element, said enclosed housing being removable from the holder as a unit together with the lateral contact spring and said first contact element.

8. A holder in accordance with claim 7, characterized in that the first contact element is resiliently tiltably supported in said wall. 

1. A holder for an electric light bulb, said bulb having a base with a center contact and a side contact, said holder comprising a socket at one end into which said bulb is pressed, two terminals for connection of electric conductors at the opposite end of said holder, said terminals being carried by a transverse plate at said opposite end, and a transverse, fixed wall intermediate said ends, one of said terminals being located in the center of said holder and the other at one side, a first, central contact element in the form of a contact pin mounted for movement through said fixed wall into contact with said center terminal by said bulb when pressed into said socket with said center contact in engagement with said first, central contact element, a spring resiliently holding said central contact element out of engagement with said center terminal unless engaged by a bulb, a fixed, lateral spring contact with one end on one side of said wall for engaging said side contact and extending toward said opposite end of said holder, with its other end on the other side of said wall, a second contact element carried by a transverse insulating carrier member mounted on said first contact element so as to be tiltable and restrictedly diSplaceable with respect thereto along the axis of the lamp holder, said second contact element being movable into engagement with the other end of said lateral spring contact and said side terminal by movement of said first contact element into engagement with said center terminal, said transverse plate together with said wall and side walls extending therebetween forming an enclosed dustproof housing for said carrier member and said second contact element, said enclosed housing being removable from the holder as a unit together with the lateral contact spring and said first contact element.
 2. A holder in accordance with claim 1, characterized in that a three-point support is arranged for the second contact element in its contact position, said three-point support comprising said other end of said lateral spring contact, said side terminal and a third support point.
 3. A holder in accordance with claim 2, characterized in that said third support point is a conductive support point which is connected to a second lateral contact spring leading to the side of said wall which faces the lamp opening.
 4. A holder in accordance with claim 2, characterized in that said insulating carrier member for the second contact element is in the form of a round plate concentrically arranged around the first contact element, and carrying at its periphery the second contact element in the form of a contact ring which projects to some extent beyond the side of the plate facing the terminals and that the support points of the three-point support are situated substantially in the same plane below the contact ring.
 5. A holder in accordance with claim 4, characterized in that the first contact element extends with some clearance through a central hole in said round plate and is terminated by a flange carrying said round plate and that a spring washer is attached at its inner periphery to the first contact element and forces the plate against the flange.
 6. A holder for an electric light bulb, said bulb having a base with a center contact and a side contact, said holder comprising a socket at one end into which said bulb is pressed, two terminals for connection of electric conductors at the opposite end of said holder, said terminals being carried by a transverse plate at said opposite end, and a transverse, fixed wall intermediate said ends, one of said terminals being located in the center of said holder and the other at one side, a first, central contact element in the form of a contact pin mounted for movement through said fixed wall into contact with said center terminal by said bulb when pressed into said socket with said center contact in engagement with said first, central contact element, a spring resiliently holding said central contact element out of engagement with said center terminal unless engaged by a bulb, a fixed, lateral spring contact with one end on one side of said wall for engaging said side contact and extending toward said opposite end of said holder, with its other end on the other side of said wall, a second contact element carried by a transverse insulating carrier member mounted on said first contact element so as to be tiltable and restrictedly displaceable with respect thereto along the axis of the lamp holder, said second contact element being movable into engagement with the other end of said lateral spring contact and said side terminal by movement of said first contact element into engagement with said center terminal, said transverse plate together with said wall and side walls extending therebetween forming an enclosed housing for said carrier member and said second contact element, said enclosed housing being removable from the holder as a unit together with the lateral contact spring and said first contact element, said side walls being fixed to said wall and depending skirt-like therefrom.
 7. A holder for an electric light bulb, said bulb having a base with a center contact and a side contact, said holder comprising a socket at One end into which said bulb is pressed, two terminals for connection of electric conductors at the opposite end of said holder, said two terminals carried by a transverse plate at said opposite end, and a transverse fixed wall intermediate said ends, one of said terminals being located in the center of said holder and the other at one side, a first, central contact element mounted for movement through said fixed wall into contact with said center terminal by said bulb when pressed into said socket with said center contact in engagement with said first, central contact element, a spring resiliently holding said central contact element out of engagement with said center terminal unless engaged by a bulb, a fixed, lateral spring contact with one end on one side of said wall for engaging said side contact and extending toward said opposite end of said holder, with its other end on the other side of said wall, a second contact element mounted on and movable by said first contact element and insulated therefrom, said second contact element being movable into engagement with the other end of said lateral spring contact and said side terminal by movement of said first contact element into engagement with said center terminal, said transverse plate together with said wall and side walls extending therebetween forming an enclosed dustproof housing for said carrier member and said second contact element, said enclosed housing being removable from the holder as a unit together with the lateral contact spring and said first contact element.
 8. A holder in accordance with claim 7, characterized in that the first contact element is resiliently tiltably supported in said wall. 